This application claims the priority of German patent document 10 2008 003669.2-31, filed Jan. 9, 2008, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a process for receiving a broadband signal, particularly for the purpose of radio reconnaissance.
Because of the maximum sampling frequency of available analog-to-digital converters, HF receivers have a limited bandwidth. This problem, can be avoided by operating several analog-to-digital converters in a time-shifted manner (time interleaving) and thereby increasing the sampling rate. However, such processes have the disadvantage that the synchronization and the control on a time and level basis of the analog-to-digital converters require high expenditures and the sampling rate or clock frequency of the converted data is very high.
Published U.S. Patent Application 2001/0014594 A1 discloses a process of receiving a broadband electromagnetic signal, which includes the following steps:                Division of the receiving spectrum into n partial spectrums, with n>1;        parallel further processing of the thus obtained n partial signals in n channels;        Demodulation of the n partial signals into the base band;        analog-to-digital conversion of the n partial signals by means of n equal-type analog-to-digital converters;        amplitude and phase correction of the n partial signals for compensating interfering edge effects at the transition to the respectively adjacent channel.        
One object of the invention to provide a receiving process with a high bandwidth for the purpose of radio reconnaissance, while the required sampling or clock rate of the used components is low.
This and other objects and advantages are achieved by the process according to the invention, in which the bandwidth of the receiver is achieved by decomposing the received signal into several partial spectrums which can then be processed in parallel, rather than by using a higher sampling in the time domain. Subsequently, the partial spectrums are joined to form a total spectrum which describes the total signal.
From the total spectrum, individual frequency bands are extracted, and are supplied, via a multiplexer to parallel subsequent processing channels for further processing. This is particularly important for radio reconnaissance when signals of unknown emitters are detected.
The frequency bands to be extracted from the total spectrum can be selected by comparing the level values with a threshold value, in each individual processing channel.
By means of the invention, it is possible to process the signal analysis in a more parallel manner, while the required processing rate/clock rate is significantly reduced. Likewise, the need for costly time synchronization between the individual analog-to-digital converters is eliminated.
Additional advantages of the invention are the following:                Signals with a very high bandwidth can be sampled.        Data are very parallelized, so that high data rates are not required for the subsequent signal processing or for the storage of the total spectrum in the RAM memory.        The signal is filed in the frequency domain rather than in the time domain. Frequency bands from the total spectrum that are of interest may be further processed by an arbitrary number of digital down converters (DDCs), which are switched in parallel and connected by way of a multiplexer, per an inverse FFT.        
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.